
/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */

package com.atom.office.fc.util;


import com.atom.office.fc.util.LittleEndian.BufferUnderrunException;

import java.io.IOException;
import java.io.InputStream;
import java.nio.BufferUnderflowException;

/**
 * representation of a byte (8-bit) field at a fixed location within a
 * byte array
 *
 * @author Marc Johnson (mjohnson at apache dot org
 */

public class ByteField implements FixedField {
    private static final byte _default_value = 0;
    private byte _value;
    private final int _offset;

    /**
     * construct the ByteField with its offset into its containing
     * byte array and a default value of 0
     *
     * @param offset of the field within its byte array
     * @throws ArrayIndexOutOfBoundsException if offset is negative
     */

    public ByteField(final int offset)
            throws ArrayIndexOutOfBoundsException {
        this(offset, _default_value);
    }

    /**
     * construct the ByteField with its offset into its containing
     * byte array and initialize its value
     *
     * @param offset of the field within its byte array
     * @param value  the initial value
     * @throws ArrayIndexOutOfBoundsException if offset is negative
     */

    public ByteField(final int offset, final byte value)
            throws ArrayIndexOutOfBoundsException {
        if (offset < 0) {
            throw new ArrayIndexOutOfBoundsException(
                    "offset cannot be negative");
        }
        _offset = offset;
        set(value);
    }

    /**
     * Construct the ByteField with its offset into its containing
     * byte array and initialize its value from its byte array
     *
     * @param offset of the field within its byte array
     * @param data   the byte array to read the value from
     * @throws ArrayIndexOutOfBoundsException if the offset is not
     *                                        within the range of 0..(data.length - 1)
     */

    public ByteField(final int offset, final byte[] data)
            throws ArrayIndexOutOfBoundsException {
        this(offset);
        readFromBytes(data);
    }

    /**
     * construct the ByteField with its offset into its containing
     * byte array, initialize its value, and write its value to its
     * byte array
     *
     * @param offset of the field within its byte array
     * @param value  the initial value
     * @param data   the byte array to write the value to
     * @throws ArrayIndexOutOfBoundsException if the offset is not
     *                                        within the range of 0..(data.length - 1)
     */

    public ByteField(final int offset, final byte value, final byte[] data)
            throws ArrayIndexOutOfBoundsException {
        this(offset, value);
        writeToBytes(data);
    }

    /**
     * get the ByteField's current value
     *
     * @return current value
     */

    public byte get() {
        return _value;
    }

    /**
     * set the ByteField's current value
     *
     * @param value to be set
     */

    public void set(final byte value) {
        _value = value;
    }

    /**
     * set the ByteField's current value and write it to a byte array
     *
     * @param value to be set
     * @param data  the byte array to write the value to
     * @throws ArrayIndexOutOfBoundsException if the offset is out
     *                                        of the byte array's range
     */

    public void set(final byte value, final byte[] data)
            throws ArrayIndexOutOfBoundsException {
        set(value);
        writeToBytes(data);
    }

    /* ********** START implementation of FixedField ********** */

    /**
     * set the value from its offset into an array of bytes
     *
     * @param data the byte array from which the value is to be read
     * @throws ArrayIndexOutOfBoundsException if the offset is out
     *                                        of range of the bte array
     */

    public void readFromBytes(final byte[] data)
            throws ArrayIndexOutOfBoundsException {
        _value = data[_offset];
    }

    /**
     * set the value from an InputStream
     *
     * @param stream the InputStream from which the value is to be
     *               read
     * @throws BufferUnderrunException if there is not enough data
     *                                 available from the InputStream
     * @throws IOException             if an IOException is thrown from reading
     *                                 the InputStream
     */

    public void readFromStream(final InputStream stream)
            throws IOException, BufferUnderrunException {
        // TODO - are these ~Field used / necessary
        int ib = stream.read();
        if (ib < 0) {
            throw new BufferUnderflowException();
        }
        _value = (byte) ib;
    }

    /**
     * write the value out to an array of bytes at the appropriate
     * offset
     *
     * @param data the array of bytes to which the value is to be
     *             written
     * @throws ArrayIndexOutOfBoundsException if the offset is out
     *                                        of the byte array's range
     */

    public void writeToBytes(final byte[] data)
            throws ArrayIndexOutOfBoundsException {
        data[_offset] = _value;
    }

    /**
     * return the value as a String
     *
     * @return the value as a String
     */

    public String toString() {
        return String.valueOf(_value);
    }

    /* **********  END  implementation of FixedField ********** */
}   // end public class ByteField

